On November 20, 2018, the US Food and Drug Administration approved emapalumab(Gamifant) for the treatment of pediatric (newborn and above) and adult patients with primary hemophagocytic lymphohistiocytosis (HLH) who have refractory, recurrent or progressive disease or intolerance with conventional HLH therapy. Developed by NovImmune SA, emapalumab is a human IgG1 antibody that targets interferon gamma. Emapalumab has received a variety of designations intended to facilitate the development of drugs for rare, serious or life-threatening diseases, including Breakthrough Therapy, Rare Pediatric Disease, and Orphan Drug designations in the US, and Priority Medicines and Orphan Drug designations in the EU. The FDA’s approval was based in part on a clinical study of 27 pediatric patients with suspected or confirmed primary HLH with either refractory, recurrent or progressive disease during conventional HLH therapy or who were intolerant of conventional HLH therapy. Results from this study showed that 63% of patients experienced a response and 70% were able to proceed to stem cell transplant. A marketing application for emapalumab is undergoing evaluation by the European Medicines Agency.

The Antibody Society is pleased and proud to be affiliated with mAbs, a multi-disciplinary journal dedicated to advancing the art and science of antibody research and development. We hope you enjoy these summaries based on the abstracts of the most read papers published in a recent issue. All the articles are open access; PDFs can be downloaded by following the links below.

MAbs Issue 10.7 (October 2018)

Platform development for expression and purification of stable isotope labeled monoclonal antibodies in Escherichia coli. In this report, Reddy et al. present the expression and purification of a stable isotope labeled mAb from a genetically engineered E. coli strain capable of forming disulfide bonds in its cytoplasm. Using 2D NMR spectral fingerprinting, they show that the unlabeled mAb and the mAb singly or triply labeled with 13C, 15N, 2H are well folded, with only minor structural differences relative to the mammalian cell-produced mAb that are attributed to the lack of glycosylation in the Fc domain.

Massive parallel screening of phage libraries for the generation of repertoires of human immunomodulatory monoclonal antibodies. Sasso et al discuss a novel approach for the generation of several novel human immunomodulatory antibodies capable of binding their targets in their native conformation and useful for therapeutic applications. They performed a massive parallel screening of phage libraries by using activated human lymphocytes to generate large collections of scFvs against 10 immune checkpoints: LAG-3, PD-L1, PD-1, TIM3, BTLA, TIGIT, OX40, 4-1BB, CD27 and ICOS. By next-generation sequencing and bioinformatics analysis, they ranked individual scFvs in each collection and identified those with the highest level of enrichment. Human IgGs from three of these collections (i.e., PD-1, PD-L1 and LAG-3) were generated and shown to have comparable or better binding affinity and biological activity than clinically validated mAbs. The repertoires generated in this work represent a convenient source of agonistic or antagonistic antibodies against the ‘Checkpoint Immunome’ for preclinical screening and clinical implementation of optimized treatments.

High-throughput screening of antibody variants for chemical stability: identification of deamidation-resistant mutants. In this report, DiCara et al describe a high-throughput method for antibody stability screening during the early stages of antibody discovery and highlight the value of broad searches of antibody sequence space. They developed a high-throughput assay to characterize asparagine deamidation and used it to identify a mutation that unexpectedly stabilizes a critical asparagine. Ninety antibody variants were incubated under thermal stress in order to induce deamidation and screened for both affinity and total binding capacity. Surprisingly, a mutation five residues downstream from the unstable asparagine greatly reduced deamidation.

Extending human IgG half-life using structure-guided design. Booth et al. report on the development of a structure- and network-based framework to interrogate the engagement of IgG with multiple Fc receptors (FcRn, C1q, TRIM21, FcγRI, FcγRIIa/b, FcγRIIIa) simultaneously. They identified features that govern Fc-FcRn interactions and identified multiple distinct pathways for enhancing FcRn binding in a pH-specific manner. Network analysis provided a novel lens to study the allosteric impact of half-life-enhancing Fc mutations on FcγR engagement, which occurs distal to the FcRn binding site. Applying these principles, they engineered a panel of unique Fc variants that enhance FcRn binding while maintaining robust biophysical properties and wild type-like binding to activating receptors.

We encourage you to join the Society to take advantage of the substantial benefits of membership, including discounts on fees for selected KNect365, CHI, and Hanson Wade meetings, discounted subscriptions to Society-affiliated journals PEDS and mAbs (special subscription rate of US $84 online only accessfor Antibody Society members) and access to information in the Members Only section of the website. In particular, we encourage members to take advantage of the discount on registration for Antibody Engineering & Therapeutics, which is the annual meeting of The Antibody Society traditionally held in San Diego in December. Membership is free for students, post-docs and employees of our corporate sponsors!

On September 28, 2018, the U.S. Food and Drug Administration (FDA) approved cemiplimab-rwlc (Libtayo)for the treatment of patients with metastatic cutaneous squamous cell carcinoma (CSCC) or locally advanced CSCC who are not candidates for curative surgery or curative radiation. Cemiplimab-rwlc is the third antibody therapeutic targeting PD1 to be granted an FDA approval, but it is the first drug to be approved in the US specifically for advanced CSCC.

FDA’s approval of Libtayo was based on a combined analysis of data from an open-label, multi-center, non-randomized Phase 2 trial known as EMPOWER-CSCC-1 (Study 1540) and two advanced CSCC expansion cohorts from a multi-center, open-label, non-randomized Phase 1 trial (Study 1423). A total of 108 patients (75 with metastatic disease and 33 with locally-advanced disease) were included in the efficacy evaluation. The confirmed objective response rate for all patients treated with Libtayo was 47%. FDA granted cemiplimab Breakthrough Therapy Designation status for advanced CSCC in 2017, and the drug’s marketing application was granted a priority review.

The Antibody Society maintains a comprehensive table of approved mAb therapeutics and those in regulatory review in the EU or US. As of Sep 28, a total of 11 antibody therapeutics had been granted first approvals in either the US or EU in 2018, and marketing applications for another 5 that have not yet been approved in either the EU or US are undergoing review in these regions. Please log into access the table in either PDF or Excel formats, located in the Members Only section.

On September 27, 2018, the U.S. Food and Drug Administration (FDA) approved galcanezumab-gnlm (Emgality)for the preventive treatment of migraine in adults. Emgality is the third antibody therapeutic approved by FDA in 2018 for this indication. As we reported in previous posts, Aimovig (erenumab-aooe) was approved on May 17, 2018 and Ajovy (fremanezumab-vfrm) was approved on September 14, 2018. The three products target either calcitonin gene-related peptide (CGRP) or the CGRP receptor. The recommended dosage of Emgality is 240 mg loading dose (administered as two consecutive injections of 120 mg each), followed by monthly doses of 120 mg.

The efficacy and safety of Emgality was demonstrated in two Phase 3 clinical trials in patients with episodic migraine (EVOLVE-1, EVOLVE-2) and one Phase 3 clinical trial in patients with chronic migraine (REGAIN). In all three studies, patients were randomized to receive once-monthly placebo, Emgality 120 mg after an initial loading dose of 240 mg, or Emgality 240 mg. In EVOLVE-1, the mean change from baseline (days) was -4.7 days (N=210) for Emgality 120 mg compared to -2.8 days (N=425) for placebo (p<0.001), while in EVOLVE-2, the mean change from baseline (days)was -4.3 days (N=226) for Emgality 120 mg compared to -2.3 days (N=450) for placebo (p<0.001). In the REGAIN study, the mean change from baseline (days) was -4.8 days (N=273) for Emgality 120 mg compared to -2.7 days (N=538) for placebo (p<0.001).

The Antibody Society maintains a comprehensive table of approved mAb therapeutics and those in regulatory review in the EU or US. As of Sep 28, a total of 10 antibody therapeutics had been granted first approvals in either the US or EU in 2018, and marketing applications for another 6 that have not yet been approved in either the EU or US are undergoing review in these regions. Please log into access the table in either PDF or Excel formats, located in the Members Only section.

The Antibody Society is pleased and proud to be affiliated with mAbs, a multi-disciplinary journal dedicated to advancing the art and science of antibody research and development. We hope you enjoy these summaries based on the abstracts of the most read papers published in a recent issue. All the articles are open access; PDFs can be downloaded by following the links below.

Issue 10.6 (Aug/Sep 2018)

Antigen recognition by single-domain antibodies: structural latitudes and constraints.In this new review, Henry and MacKenzie comprehensively surveyed the evidence in support of the hypothesis that sdAbs may adopt paratope structures that predispose them to preferential recognition of recessed protein epitopes, but poor or non-recognition of protuberant epitopes and small molecules. They found some support for a global structural difference in the paratope shapes of sdAbs compared with those of conventional antibodies. Comparison of X-ray crystal structures of sdAbs and conventional antibodies in complex with cognate antigens showed that sdAbs and conventional antibodies bury similar solvent-exposed surface areas on proteins and form similar types of non-covalent interactions, although these are more concentrated in the compact sdAb paratope. Thus, the authors conclude that sdAbs likely have privileged access to distinct antigenic regions on proteins, but only owing to their small molecular size and not to general differences in molecular recognition mechanism. The evidence surrounding the purported inability of sdAbs to bind small molecules was less clear. The available data provide a structural framework for understanding the evolutionary emergence and function of autonomous heavy chain-only antibodies.

Homology modeling and structure-based design improve hydrophobic interaction chromatography behavior of integrin binding antibodies.In this new report, Jetha et al. optimized a candidate integrin α11-binding mAb for developability using molecular modeling, rational design, and hydrophobic interaction chromatography (HIC). A homology model of the parental mAb Fv region was built, and this revealed hydrophobic patches on the surface of the complementarity-determining region loops. A series of 97 variants of the residues primarily responsible for the hydrophobic patches were expressed and their HIC retention times (RT) were measured. As intended, many of the computationally designed variants reduced the HIC RT compared to the parental mAb, and mutating residues that contributed most to hydrophobic patches had the greatest effect on HIC RT. A retrospective analysis was then performed where 3-dimentional protein property descriptors were evaluated for their ability to predict HIC RT using the current series of mAbs. The same descriptors were used to train a simple multi-parameter protein quantitative structure-property relationship model on this data, producing an improved correlation. This analysis was extended to recently published HIC data for 137 clinical mAb candidates as well as 31 adnectin variants, and the authors found that the surface area of hydrophobic patches averaged over a molecular dynamics sample consistently correlated to the experimental data across a diverse set of biotherapeutics.

Heterologous recombinant expression of non-originator NISTmAb.Kashi et al. describe the development and initial expression of an intended copy of the NISTmAb using three non-originator murine cell lines. The authors found that, without optimization and in culture flasks, all three cell lines produce approximately 100 mg mAb per liter of culture. SDS-PAGE, SEC, NMR spectroscopy, intact MS, and SPR were used to demonstrate that the products of all three cell lines embody quality attributes with a sufficient degree of sameness to the NISTmAb Reference Material 8671 to warrant further bioreactor studies, process improvements and optimization. The implications of the work with regard to pre-competitive innovation to support process design and feedback control, comparability and biosimilarity assessments, and process analytical technologies are discussed.

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We encourage you to join the Societyto take advantage of the substantial benefits of membership, including discounts on fees for selected KNect365, CHI, and Hanson Wade meetings, discounted subscriptions to Society-affiliated journals PEDS and mAbs (special subscription rate of US $84online only access for Antibody Society members) and access to information in the Members Only section of the website. In particular, we encourage members to take advantage of the discount on registration for Antibody Engineering & Therapeutics,which is the annual meeting of The Antibody Society traditionally held in San Diego in December. Membership is free for students, post-docs and employees of our corporate sponsors!